Protocol Messages

Our protocol contains the following message types:

transaction start

The T-start message is used to begin a transaction. This message contains:

1. the identity certificate of the sender
2. the signature

transaction accept

The T-accept message is sent in response to a T-start message if the process decides to accept the transaction. This message contains:

1. the TID from the T-start message
2. the process's own identity certificate
3. the signature

transaction data

Once the transaction has been established, the processes may exchange data with T-data messages. These messages contain:

1. the TID
2. the data
3. the context
4. the signature

transaction token

Communication in STP is half duplex. When one process is through sending T-data messages, it will send a T-token message to allow the other process to transmit. This message contains:

1. the TID
2. the context
3. the signature

transaction commit

When a process wishes to conclude a transaction successfully, it sends a T-commit message to the other process. This message contains:

1. the TID
2. the context
3. the signature

transaction abort

When a transaction wishes to terminate a transaction without commitment, it sends a T-abort message to the other process. This message contains:

1. the TID
2. the signature

transaction fault

If there is a failure in communications, the communication system will `send' a T-fault message to the process for each message sent by that process which cannot be delivered with the defined semantics. This message contains the TID for the transaction during which the message was sent. Note that the T-fault message does not indicate that the message was not transmitted correctly, but only that the communication subsystem cannot verify the correct transmission.